This was lunch for Monarchs; as such, only Monarchs or their representatives (such as Lalla Meryem in place of King of Morocco) were present, plus most members of the British Royal Family. Given the close relationship between Prince Charles and Princess Margareta, I have little doubts she and Prince Radu were invited to the dinner which is to take place in mere hours.

Actually the Princess was there. I checked on the images from PA, and saw a picture of her arriving with her father.

I also love this picture of Elizabeth and Beatrix because you can see that they genuinely like each other and are friends. The expression on Beatrix's face is just so happy and joyful. You can definitely see where Amalia gets her spark and spirit.